Epidemiological Investigation On Classical Swine Fever In Shandong Province

Classical Swine Fever (CSF) is a highly contagious and often fatal disease of pigs caused by Classical Swine Fever Virus (CSFV), a member of the genus Pestivirus within the family Flaviviridae. Although the implementation of statutory vaccination program is effective in control of the disease without major outbreaks, the CSF is still sporadic in China, causing a complicated situation with a huge economic lost every year. To get overall information about the prevalence of CSFV in Shandong province, we conducted a serological and molecular epidemiological investigation.1. In this study, 708 serum samples collected from 13 Pig farms in Shandong province were detected for antibodies against CSFV by ELISA. 501 samples were positive presenting a overall positive rate as 70.7%. Of which, breeding flocks,newborn piglets, weaning piglets and finishing pigs showed different positive percentage corresponding to 80.3%, 78.2%, 73.5% and 64% respectively.2. 315 CSF suspect samples were detected by RT-PCR Kits for identification of CSFV, 51 were positive giving a positive rate as 16.2%. Out of the 51 positive, 12 samples were randomly selected. E2 gene fragment, the major antigen encoding region of CSFV, was respectively cloned and sequenced. Phylogenetic analysis showed that all the 12 isolates belonged to CSFV group 2. Of which, 10 isolates including SDWF-1, SDWF-2, SDWF-3, SDWF-4, SDZB-1, SDYT-1, SDDZ-1, SDHZ-1, SDJN-1, SDQD-1 belonged to subgroup 2.1, whereas the remaining 2, SDTA-1 and SDTA-02, were clustered to subgroup 2.2. The results indicated that genotype 2.1 of CSFV was predominant in Shandong province.